Round balers for compaction of an agricultural crop are known. Among others, there are balers in use that have variable bale chambers in which one or more moving forming belts guided over rollers delimit a bale chamber in the circumferential direction of a round bale that is to be formed. Right and left side walls of the round baler delimit the bale chamber in the forward direction of travel on the side, or face, of a cylindrical round bale that is to be formed.
In general, round balers are towed by a towing vehicle, for example, an agricultural tractor, over a swath of cut or mown crop laid on the ground, where a pickup and feed unit on the round baler picks up the crop and transports it to the bale chamber. A cylindrical bale forms with increasing crop feed. It is disadvantageous that frequently the forming belt or belts wander or drift laterally with respect to their circumferential direction, so that for one asymmetric bales can result, and for another the forming belts can rub or drag along at the side walls and unnecessarily wear. A lateral drift is, as a rule, caused by crop that is not uniformly delivered over the width of the round baler. This may be because the swath laid on the ground is unevenly piled up, or the round baler is not guided over the middle of the swath. Thus, more crop is fed to the bale chamber on one side of the baler than on the other side, which unevenly tensions the forming belt or belts over the width of the bale chamber. This ultimately gives rise to a lateral wandering or drifting of the forming belt and in the worst case lets the belt reach the side wall, at which it then drags along, which should be prevented. A driver of the vehicle may prevent this by guiding the baler appropriately evenly over the swath so that a crop feed uniformly distributed over the width of the round baler takes place. However, this is difficult because the driver lacks information about the uniformity of the delivered amount of crop.
Thus, there is a need for a round baler designed with which crop feed that is as uniform as possible can take place, so that cylindrical bales can be uniformly formed and the wear of a forming belt can be reduced.